胜坨地区高密度水泥浆体系的设计与应用

针对胜坨地区油气井原始地层压力高,固井作业时易发生气窜等问题,进行了高密度抗盐水泥浆体系研究。应用紧密堆积和颗粒级配原理,使用微硅与铁矿粉进行颗粒级配,并优选了铁矿粉和沃尔德的外加剂,配制出高性能的高密度水泥浆体系。对该水泥浆的稳定性、稠化时间、防气窜性能、流变性能进行了室内评价,试验表明,该体系在较大温度范围内具有浆体沉降稳定性好、密度在1.90~2.60 g/cm3范围内可调、游离液为零、流变性好、失水量小、强度高、稠化时间可调等特点,而且具有良好的防气窜性能。该高密度水泥浆体系已成功应用于胜坨地区坨720等井以及胜利油田、新疆等高压油气层地区固井作业中,现场应用表明,该体系的流变性能、初始稠度、失水量、稠化时间、抗压强度等指标均能满足施工要求,固井质量优良,可进一步推广应用。

Design and application of high density cement slurry in Shengtuo region

Research on high density salt tolerant cement slurry is carried out to solve the problems of the high initial layer pressure of oil and gas wells and the gas migration while cementing in Shengtuo region. According to the principles of high packing and granularity, microsilica and iron ores are used for grain composition, iron ores and additives produced by the World Company are selected to develop high performance and high density cement slurry. What's more, laboratory evaluation on the stability, thickening time, preventing gas-channeling properties, and rheological properties of this cement slurry is conducted. The experimental results show that the high density cement slurry has properties of stable sedimentation, adjustable density ranging from 1.90 g/cm3 to 2.60 g/cm3, no free liquid, good rheological property, low fluid loss, high strength, adjustable thickening time, and excellent preventing gas-channeling properties. It has been successfully applied to Tuo720 well of Shengtuo region as well as well cementing operation of high pressure oil and gas reservoirs in Shengli Oilfield and Xinjiang, etc The field application shows that the indexes of the system such as rheological property, initial consistency, fluid loss, thickening time, and compressive strength fulfill the demand of construction. Good cementing results have been achieved and it is possible to be more popularized and applied.